Data and Analysis

Average Annual Daily Traffic (AADT)

The annualized average 24-hour volume of vehicles at a given point or section of highway is called a traffic count. It is normally calculated by determining the volume of vehicles during a given period and dividing that number by the number of days in that period.

How We Obtain Traffic Counts

Automatic Traffic Recorder (ATRs)

The ATRs collect data 24 hours a day, 365 days annually, for each lane. The equipment records traffic volumes, speed and classification of vehicles. MPD uses this data to develop seasonal factors, daily factors, axle factors and estimate vehicle miles of travel (VMT). These factors are applied to all coverage counts.

Coverage Counts

Coverage counts are needed to ensure that adequate geographic coverage exists for all roads under the jurisdiction of the state highway authority. In simple terms, coverage counts are data collection efforts that are undertaken to ensure that at least some data exist for all roads maintained by the agency.